Hello Jakub,

There are other DLS instruments that can measure the zeta potential of clays, hydroxides and zeolites, however I understand that normally the measurement of such properties require quite dilute suspensions (to eliminate multiple scattering and give good electrophoretic mobility data). The Malvern ZS and the Advance use a non-invasive backscattering technique whereby the laser and lens can focus on the a tiny surface of the sample and get good data on even concentrated dispersions (up to 40% solids apparently). This along with some other software functions such as their adaptive correlation (which can eliminate spurious data from dust particles and the like) make it much more usable than other systems. If it were my lab, I'd be pushing Malvern for a discounted price, rather than looking at cheaper instruments.

As a full disclosure, I did previously work at Malvern although in a different product line. I hope this helps,

Best regards,

Phil

Hi Philip,

Thanks for your advice and comment. Malvern devices are indeed of high quality. I've used ZS several times in the past with good results. I was just curious wheather someone would suggest any other option from their experience.

Best regards,

Jakub

Commercial light scattering instruments are pretty similar, especially if they offer the PALS method (which I developed for my PhD). The Zetasizer isn't perfect. It has it's very real limitations, as do other instruments. I still experience many WTF moments when I investigate exactly how each manufacturer implemented the basic technique. e.g., the Zetasizer is overly complicated and introduces unnecessary solutions to problems that only the Zetasizer has. Such problems were solved in the 1970s.

One thing not mentioned is the concentration of samples of interest. If you are routinely monitoring opaque/high solid content samples, you may be better off considering other techniques such as those based on ultrasonics. They also have their limitations.

Irrespective of the chosen technology, it is important not to treat them like black boxes. It's all to easy to use a Zetasizer (and similar) as nothing more than a UV/vis spectrophotometer. Failure to understand the fundamentals of the technique and a given implementation's limitations can lead to a lot of heartache and wasted effort.